On 4/1/22 8:29 PM, Andrii Nakryiko wrote:
> Last part of architecture-agnostic user-space USDT handling logic is to
> set up BPF spec and, optionally, IP-to-ID maps from user-space.
> usdt_manager performs a compact spec ID allocation to utilize
> fixed-sized BPF maps as efficiently as possible. We also use hashmap to
> deduplicate USDT arg spec strings and map identical strings to single
> USDT spec, minimizing the necessary BPF map size. usdt_manager supports
> arbitrary sequences of attachment and detachment, both of the same USDT
> and multiple different USDTs and internally maintains a free list of
> unused spec IDs. bpf_link_usdt's logic is extended with proper setup and
> teardown of this spec ID free list and supporting BPF maps.
>
> Reviewed-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
> Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> ---
> tools/lib/bpf/usdt.c | 168 ++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 167 insertions(+), 1 deletion(-)
[...]
> diff --git a/tools/lib/bpf/usdt.c b/tools/lib/bpf/usdt.c
> index c9eff690e291..afbae742c081 100644
> --- a/tools/lib/bpf/usdt.c
> +++ b/tools/lib/bpf/usdt.c
[...]
> +static size_t specs_hash_fn(const void *key, void *ctx)
> +{
> + const char *s = key;
> +
> + return str_hash(s);
> +}
> +
> +static bool specs_equal_fn(const void *key1, const void *key2, void *ctx)
> +{
> + const char *s1 = key1;
> + const char *s2 = key2;
> +
> + return strcmp(s1, s2) == 0;
> +}
IIUC, you're not worried about diabolical strings in strcmp and str_hash here
because of sanity checking in parse_usdt_note?
Anyways,
Reviewed-by: Dave Marchevsky <davemarchevsky@xxxxxx>
